(1) Field of the Invention
This invention relates to a mechanical snubber to be interposed between a support body and a load to be supported thereon, the snubber being constructed to permit slow relative displacements of the support body and load while restricting quick motions of the load relative to the support body.
(2) Description of the Prior Art
The snubbers which are used for snubbing vibrations of pipings in nuclear or chemical plants are required on one hand to permit slow displacements of pipings as caused by thermal expansion thereof and on the other hand to be able to restrict quick or abrupt motions of the pipings sufficiently at the time of earthquakes or on other occasions. The known oil dampers can serve for these purposes but they have a problem in that the periodical maintenance and service which is necessary to check for deteriorations of the oil is practically difficult especially when they are installed in those places which are under influence of nuclear radiation. Therefore, there have been developed and widely used the so-called mechanical type vibration snubbers in place of the oil type snubbers.
An example of such mechanical snubber is disclosed in U.S. Pat. No. 4,236,606, where the snubber is provided with a rotary body which is rotated in relation with externally induced linear motion, an inertia member which is disposed opposingly to the rotary body and rotationally connectible therewith through interposed balls serving as rotation control means as long as the externally induced linear motion is of small momentum to permit displacement of the snubber. When the externally induced linear motions is of high momentum, the inertia member is lagged behind the rotatable body in rotation and moved away therefrom to generate a braking force.
However, the prior art snubber has a high dynamic spring constant at the natural frequency of vibration of the unit (as will be discussed in greater detail hereinlater), so that there is possibilities of imposing a great load on the piping or other supported body and instabilizing the vibration snubbing action due to resonance of the inertia member.